Semiconductor processing methods for forming electrical contacts

ABSTRACT

Electroless plating can be utilized to form electrical interconnects associated with semiconductor substrates. For instance, a semiconductor substrate can be formed to have a dummy structure thereover with a surface suitable for electroless plating, and to also have a digit line thereover having about the same height as the dummy structure. A layer can be formed over the dummy structure and digit line, and openings can be formed through the layer to the upper surfaces of the dummy structure and digit line. Subsequently, a conductive material can be electroless plated within the openings to form electrical contacts within the openings. The opening extending to the dummy structure can pass through a capacitor electrode, and accordingly the conductive material formed within such opening can be utilized to form electrical contact to the capacitor electrode.

TECHNICAL FIELD

The invention pertains to semiconductor processing methods for formingelectrical contacts, and also pertains to semiconductor structures.

BACKGROUND OF THE INVENTION

Semiconductor fabrication processes frequently involve formation ofelectrical interconnects within openings. The desired aspect ratio ofthe openings is increasing for various reasons, including, for example,to compensate for losses in capacitance or inductance. As the aspectratio increases, it becomes increasingly difficult to conformally fillopenings with traditional processes. FIGS. 1 and 2 illustrate anexemplary prior art process, and a problem that can occur during anattempt to form an electrical interconnection within an opening.

FIG. 1 shows a semiconductor construction 10 at a preliminary processingstage. Construction 10 comprises a base 12. The base can comprise,consist essentially of, or consist of monocrystalline siliconlightly-doped with background p-type dopant. The base 12 can be referredto as a “substrate”, and/or various combinations of structures can bereferred to as a “substrate”. To aid in interpretation of the claimsthat follow, the terms “semiconductive substrate” and “semiconductorsubstrate” are defined to mean any construction comprisingsemiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” refers to any supporting structure,including, but not limited to, the semiconductive substrates describedabove.

A conductive block 14 is formed over base 12. Block 14 can correspondto, for example, a digit line.

An insulative material 16 is formed over base 12 and over block 14.Insulative material 16 can comprise, for example, borophosphosilicateglass (BPSG).

An opening 18 is etched through insulative material 16 to an uppersurface of conductive block 14. Opening 18 can be formed utilizing, forexample, photolithographic processing to generate a patternedphotoresist mask (not shown) which defines a location for opening 18,followed by an etch into material 16 to generate the opening 18, andsubsequent removal of the photoresist mask. The opening is shown havingvertical sidewalls, but it is to be understood that such is an idealizedstructure. Frequently the opening will have non-vertical sidewalls dueto limitations in etching processes.

Referring to FIG. 2, a first conductive material 20 is formed overinsulative material 16 and within opening 18. Conductive material 20 cancomprise, for example, a metal nitride (such as titanium nitride) andcan be formed by, for example, chemical vapor deposition. A secondconductive material 22 is formed over conductive material 20. Secondconductive material 22 can comprise, for example, tungsten and can alsobe formed by, for example, chemical vapor deposition. The first layer 20can function as an adhesive for adhering the second layer 22 toinsulative material 16.

A problem that occurs during deposition of one or both of materials 20and 22 is that the conductive material can grow non-conformally at uppercorners proximate opening 18 to form extensions 24. The extensions 24can ultimately pinch off the top of opening 18 before the opening hasbeen conformally filled with conductive materials 20 and 22.Accordingly, a void 26 remains in the opening. Such void is frequentlyreferred to as a “keyhole”. The shape of the opening 18 and keyhole 26are shown diagrammatically in FIGS. 1 and 2, and it is to be understoodthat the opening and keyhole can have other shapes. Such other shapescan include a concave “bow” near the top of opening 26 due tolimitations in the ability of etches to form the shown verticalsidewalls. The bow can provide additional complications to a conformalfill which can exacerbate keyhole problems and lead to formation oflarge keyholes just below the upper surface of material 16. Such largekeyholes can undesirably be exposed in subsequent polishing processes.It is desired to develop new methods for filling openings whichalleviate, and preferably prevent, formation of keyholes.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a semiconductor processingmethod for forming an electrical contact. A semiconductor substrate isprovided. The substrate has a surface suitable for electroless plating,a layer over the surface, and a node supported by the layer. An openingis formed through the layer and to the suitable surface. A periphery ofthe opening includes an electrically conductive portion of the node. Aconductive material is electroless plated within the opening, with theelectroless plating being initiated from the suitable surface. Theelectroless-plated material forms an electrical contact to the node.

In one aspect, the invention encompasses a semiconductor processingmethod for forming electrical contacts to a capacitor electrode and adigit line. A semiconductor substrate is provided. The substratesupports a digit line and a spacer structure. The digit line comprises aregion, and the spacer structure comprises another region. The digitline region has an upper surface, and the spacer structure region hasanother upper surface. The digit line region upper surface is at aboutthe same elevational height over the substrate as the spacer structureregion upper surface. The semiconductor substrate further compriseselectrically insulative material over the digit line region and thespacer structure region, and a capacitor electrode supported by theinsulative material. Openings are formed through the insulativematerial. One of the openings is a first opening that extends to theupper surface of the digit line region, and another of the openings is asecond opening and extends to the upper surface of the spacer structureregion. The second opening has a periphery which includes anelectrically conductive portion of the capacitor electrode. A conductivematerial is electroless plated within the first and second openings. Theelectroless plating initiates from the upper surfaces of the digit lineregion and the spacer structure region. The electroless-plated materialforms an electrical contact with the digit line in the first opening,and forms an electrical contact with the capacitor electrode in thesecond opening. The spacer structure can be referred to as a “dummy”structure in particular aspects of the invention to indicate that thestructure is an electrical dead-end and thus comprises no electricalpurpose. The spacer structure instead has the physical purpose ofmimicking the height of the digit line. In other words, the term “dummystructure” is to be understood herein as referring to a structure whichis utilized to mimic a physical property of another structure (such asto mimic the height of a digit line structure), and which is circuitinoperable (i.e., which is not part of a current flow path of acircuit). The dummy structure can comprise a single layer or acombination of different layers.

In one aspect, the invention encompasses a semiconductor structure. Thestructure includes a semiconductor substrate, a digit line supported bythe substrate, and a spacer structure supported by the substrate. Thedigit line can comprise a single layer or multiple layers, andfrequently will comprise a stack of TiN/silicon/WSi_(x); similarly, thespacer structure can comprise a single layer or multiple layers. Thedigit line comprises a first region having an upper surface at a firstelevational height over the semiconductor substrate. The spacerstructure comprises a second region having an upper surface at anelevational height over the substrate which is about the same as thefirst elevational height. The spacer structure is a dummy structure. Thesemiconductor structure includes electrically insulative materialsupported by the semiconductor substrate. The electrically insulativematerial is over the digit line and the spacer structure regions. Acapacitor structure is supported by the insulative material. Thecapacitor structure includes a first capacitor electrode, a secondcapacitor electrode and at least one dielectric material between thefirst and second capacitor electrodes. A first conductive interconnectextends upwardly from the digit line region and through the insulativematerial, and a second conductive interconnect extends upwardly from thespacer structure region, through only one of the first and secondcapacitor electrodes, and through the insulative material. The first andsecond conductive interconnects are of the same composition as oneanother.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic, cross-sectional view of a semiconductor waferfragment shown at a preliminary prior art processing stage.

FIG. 2 is a view of the FIG. 1 wafer fragment shown at a prior artprocessing stage subsequent to that of FIG. 1.

FIG. 3 is a diagrammatic, cross-sectional view of a semiconductor waferfragment shown at a preliminary processing stage of an exemplary methodof the present invention.

FIG. 4 is a view of the FIG. 3 wafer fragment shown at a processingstage subsequent to that of FIG. 3.

FIG. 5 is a view of the FIG. 3 wafer fragment shown at a processingstage subsequent to that of FIG. 4.

FIG. 6 is a diagrammatic, cross-sectional view of a semiconductor waferfragment shown at a preliminary processing stage alternative to that ofFIG. 3.

FIG. 7 is a view of the FIG. 6 wafer fragment shown at a processingstage subsequent to that of FIG. 6.

FIG. 8 is a view of the FIG. 6 wafer fragment shown at a processingstage subsequent to that of FIG. 7.

FIG. 9 is a view of the FIG. 6 wafer fragment shown at a processingstage subsequent to that of FIG. 8.

FIG. 10 is a view of the FIG. 6 wafer fragment shown at a processingstage subsequent to that of FIG. 6, and in accordance with an embodimentof the invention alternative to the embodiment described previously withreference to FIGS. 7–9.

FIG. 11 is a view of the FIG. 3 wafer fragment shown at a processingstage subsequent to that of FIG. 4 in accordance with a fourth aspect ofthe invention.

FIG. 12 is a view of the FIG. 3 wafer fragment shown at a processingstage subsequent to that of FIG. 11 in accordance with the fourth aspectof the invention.

FIG. 13 is a diagrammatic view of a computer illustrating an exemplaryapplication of the present invention.

FIG. 14 is a block diagram showing particular features of themotherboard of the FIG. 13 computer.

FIG. 15 is a high-level block diagram of an electronic system accordingto an exemplary aspect of the present invention.

FIG. 16 is a simplified block diagram of an exemplary memory deviceaccording to an aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

The invention includes methods which utilize electroless plating to formelectrical interconnects within openings. An advantage of electrolessplating is that such can be conducted to fill an opening from the bottomof the opening to the top, and accordingly can fill high aspect ratioopenings without the prior art problem of pinching off a top of theopening during the fill process.

One aspect of the invention is to utilize electroless plating to forminterconnects to two or more circuit structures which are at differentelevational heights relative to one another. FIG. 3 illustrates asemiconductor construction 50 which can be utilized in such aspect ofthe invention. Construction 50 comprises a base 52 which can comprisemonocrystalline silicon, and which can have the same construction asdiscussed previously with reference to the base 12 of FIGS. 1 and 2. Aconductive structure 54 is formed over base 52. Structure 54 cancorrespond to, for example, a digit line. Although the structure isshown being uniformly conductive throughout its thickness, it is to beunderstood that the structure can comprise layers of electricallyinsulative and electrically conductive materials. The uppermostconductive material will have a top surface, and such top surfacecorresponds to an uppermost conductive surface 55 of structure 54. Ifstructure 54 comprises a stack of electrically insulative andelectrically conductive materials, the top surface 55 can be theuppermost surface of the stack, or can be covered by an electricallyinsulative cap. Regardless, the upper conductive surface will typicallyultimately be exposed in subsequent processing, such as, for example,the processing described below with reference to FIG. 4.

The FIG. 3 structure comprises an electrically insulative layer 56 overbase 52 and over structure 54. Electrically insulative layer 56 cancomprise any suitable material, including, for example, BPSG.

A capacitor structure 58 is supported by electrically insulative layer56. Capacitor structure 58 comprises a first capacitor electrode 60, asecond capacitor electrode 62, and at least one dielectric material 64between capacitor electrodes 60 and 62. Capacitor electrodes 60 and 62can comprise any suitable electrically conductive materials, including,for example, metals, metal compositions, and/or conductively-dopedsilicon. In particular aspects, electrode 60 corresponds to a storagenode of the capacitor and electrode 62 corresponds to a plate electrodeof the capacitor. One or both of the capacitor electrodes can, in someaspects, comprise conductively-doped silicon (such as conductively-dopedpolycrystalline silicon) and/or a metal composition, such as, forexample, one or more of TiN, WN and WSi; with the listed compositionsbeing shown in terms of the elements contained therein rather than interms of a particular stoichiometry of the elements within thecompositions.

The dielectric material 64 can comprise any suitable material,including, for example, one or more of silicon dioxide, silicon nitride,and various high-k dielectric materials.

Capacitor storage node 60 is shown electrically connected to atransistor device 69. As is known to persons of ordinary skill in theart, transistor device 69 would typically comprise a gate (not shown)and a pair of source/drain regions (not shown). Storage node 60 would beconnected to one of the source/drain regions, and the other of thesource/drain regions would be connected to a bit line (or digit line)(not shown). Accordingly, the transistor gate would gatedly connectstorage node 60 to the bit line. The capacitor structure 58 thus can beutilized as a memory storage unit of a memory cell. Specifically, thecombination of a transistor structure with a capacitor is a typical unitcell of a dynamic random access memory (DRAM) device. A plurality of thecapacitors and transistors can be incorporated into a DRAM array, as isknown to persons of ordinary skill in the art.

The shown capacitor construction 58 comprises storage node 60 in acontainer shape, and comprises dielectric material 64 and capacitorplate electrode 62 extending within the container shape of storage node60. The shown capacitor construction also compriseshorizontally-extending segments 66 and 68 laterally adjacent theportions of the materials 64 and 62 within the container opening.Horizontally-extending segments 66 and 68 can be exactly horizontal, canbe substantially horizontal, or can simply be horizontal relative toportions of materials 64 and 62 along the sidewalls of the containeropening. Capacitor plate electrode 62 has an upper surface 63 whichextends along the horizontally-extending segments 66 and 68, and whichalso extends within the container shape of storage node 60. Theillustrated capacitor construction is an exemplary construction, and itis to be understood that numerous other shapes of capacitorconstructions can be utilized in various aspects of the invention.

As discussed previously, the term “substrate” is defined herein to bebroad enough to encompass any supporting structure or combination ofstructures, and the term “semiconductor substrate” is broad enough toencompass any combination of structures provided that one of thestructures contains a semiconductor material. Accordingly, either base52 or structure 54 can be considered a substrate in various aspects ofthe invention, and also the combination of structure 54 and base 52 canbe considered a substrate (or semiconductor substrate) in variousaspects of the invention. Additionally, capacitor structure 58 can beconsidered a substrate in various aspects of the invention, and can beconsidered a semiconductor substrate if either of the electrodescomprises conductively-doped silicon. Further, the combination ofcapacitor 58 with base 52 can be considered a semiconductor substrate.Also, the combination of capacitor structure 58, layer 56 and base 52can be considered a semiconductor substrate, as can the combination ofcapacitor 58, layer 56, structure 54 and base 52.

Although layer 56 is shown comprising a homogeneous composition, it isto be understood that the layer can be replaced with a stack of layers.The stacked layers can have the same composition as one another ordifferent compositions. Also, although the same material 56 is shownover the structure 54 and around the capacitor 58, it is to beunderstood that different insulative materials can be over the structure54 than are around the capacitor 58 in some aspects of the invention.Thus, the insulative material over structure 54 can be referred to as afirst insulative material and the insulative material proximate thecapacitor 58 can be referred to as a second insulative material. In theshown aspect of the invention, the first and second insulative materialsare comprised by common layer 56, and in other aspects of the inventionthe first and second insulative materials can differ from one another.Further, although the material of layer 56 is shown both above and belowcapacitor 58, it is to be understood that a different insulativematerial can be over capacitor 58 than is under capacitor 58 in someaspects of the invention. If the insulative material over the capacitoris different than the insulative material under the capacitor, theinsulative material under the capacitor can be referred to as a layersupporting the capacitor and the insulative material over the capacitorcan be referred to as being supported by the capacitor.

Referring to FIG. 4, openings 70 and 72 are etched through layer 56 toupper surface 63 of capacitor structure 58 and to upper surface 55 ofconductive structure 54. Openings 70 and 72 can be formed utilizingphotolithographic processing and an appropriate etch. Specifically,photolithographic processing can be used to form a patterned photoresistmask (not shown) which defines the locations of openings 70 and 72, asubsequent etch can be used to form the openings through layer 56, andthen the photoresist mask can be removed.

Openings 70 and 72 have a comparable width to one another, but opening70 is much deeper than is opening 72. For instance, opening 70 can havea depth of about 3 microns and opening 72 can have a depth of about 1micron in particular aspects of the invention. In other words, athickness of layer 56 over segment 68 of capacitor structure 58 can beabout 1 micron and a thickness of layer 56 over upper surface 55 ofconductive structure 54 can be about 3 microns in particular aspects ofthe invention.

Although layer 56 is shown as a homogeneous material, at least a portionof layer 56 can be replaced by a stack of insulative materials asdiscussed previously. In such aspects of the invention, at least one ofopenings 70 and 72 can extend through the stack of insulative materials.

Referring to FIG. 5, a conductive material 80 is electroless platedwithin openings 70 and 72 to form electrical interconnects 82 and 84extending within openings 70 and 72, respectively. Conductive material80 can comprise, consist essentially of, or consist of, for example, oneor more of palladium, zinc, silver, nickel and cobalt. In particularaspects, conductive material 80 will comprise, consist essentially of,or consist of nickel, cobalt, nickel-containing alloys orcobalt-containing alloys.

The electroless plating initiates at upper surfaces 55 and 63 ofstructures 54 and 62, and accordingly conductive material 80 growswithin openings 70 and 72 from the bottoms of the openings to the topsof the openings. Such bottom-up growth can uniformly fill the openings.

As is known to persons of ordinary skill in the art, electroless platinginitiates from surfaces which are suitable for the electroless plating.A surface suitable for electroless plating is a surface on which theelectroless plating self-initiates from a bath rather than requiring acatalyst to initiate. Suitable surfaces can comprise, for example, oneor more of palladium, zinc, silver, nickel and cobalt. Thus, surfaces 55and 63 can be rendered suitable for initiation of electroless plating byforming the surfaces from materials comprising, consisting essentiallyof, or consisting of one or more of palladium, zinc, silver, nickel andcobalt. In some aspects, surfaces 55 and 63 can comprise compositionssuitable for electroless plating prior to formation of layer 56 over thesurfaces. Alternatively, surfaces 55 and 63 can be formed ofcompositions which are not suitable for electroless plating, and whichare subsequently activated after formation of openings 70 and 72. Thesurfaces can be activated by exposing the surfaces to one or more ofnickel, cobalt, palladium, zinc and silver to either incorporate one ormore of nickel, cobalt, palladium, zinc and silver into the compositionof the upper surfaces or to form a layer containing one or more ofnickel, cobalt, palladium, zinc and silver over the upper surfaces.Thus, the composition of surfaces 55 and 63 can be, in particularaspects of the invention, unsuitable for electroless plating when layer56 is formed over the surfaces, and then portions of the surfaces can berendered suitable for electroless plating after such portions areexposed through openings 70 and 72.

Compositions unsuitable for electroless plating are typicallycompositions which do not contain at least one of nickel, cobalt,palladium, zinc or silver in sufficient quantity to initiate electrolessplating. Compositions suitable for initiation of electroless platingwithout activation can be referred to as “self-catalyzing” surfaces, andsurfaces needing activation to be suitable for initiation of electrolessplating can be referred to as “non-self-catalyzing” surfaces.

In particular aspects of the invention, opening 72 will have a depthwhich is much less-than the depth of opening 70. The electroless platingwill form about the same amount of material within opening 72 as isformed within opening 70. Accordingly, formation of sufficient materialto fill opening 70 will result in a large amount of excess materialformed over opening 72. Thus, a large hump of excess material is shownformed over opening 72, and a substantially smaller hump of material isshown formed over opening 70. The disparity in the thickness of excessmaterial 80 over opening 72 relative to the thickness over opening 70can complicate subsequent processing. Specifically, it can be difficultto remove the excess conductive material by planarization when thethickness of the excess material has a large variation across the uppersurface of layer 56. Additionally, if spacing between 70 and 72 is halfof the height difference, material 80 overfilling opening 72 can pinchoff opening 70 before opening 70 is filled.

FIGS. 6–8 illustrate an aspect of the invention which alleviates thedisparate thicknesses of material 80 over openings 70 and 72. Referringinitially to FIG. 6, a construction 100 is illustrated at a preliminaryprocessing stage of a second embodiment aspect of the present invention.Construction 100 comprises a number of features identical to thosedescribed previously with reference to FIGS. 3–5, and such features arelabeled the same in FIG. 6 as they were labeled in FIGS. 3–5.

The construction 100 of FIG. 6 differs from the construction 50 of FIGS.3–5 in that a spacer structure 102 is provided in construction 100.Spacer structure 102 comprises a conductive material 104 having an uppersurface 105, and is illustrated shaped as a block in the cross-sectionalview of FIG. 6. Upper conductive surface 105 typically comprises thesame chemical composition as upper conductive surface 55 of structure54. Further, upper conductive surface 105 has about the same elevationalheight over base 52 as does upper conductive surface 55. Accordingly,structure 102 can be considered a spacer having an upper conductivesurface 105 spaced from base 52 by about the same distance as uppersurface 55 of structure 54 is spaced from base 52.

Structure 102 can be referred to as a “dummy” structure if the structurehas no purpose except to space upper conductive surface 105 from base52. In such aspects, structure 102 is not connected to circuit devices,and ultimately is an electrical dead end for any electrical interconnectthat extends to structure 102. In particular aspects of the invention,structure 54 is a digit line and structure 102 is a “dummy” structurethat mimics at least the portion of the digit line where an electricalinterconnection is ultimately to be formed.

The digit line 54 will extend into and out of the page in the showncross section of FIG. 6. Accordingly, the portion of the digit lineshown in FIG. 6 corresponds to a specific region of the digit line.Other regions of the digit line can have a different thickness ofconductive material than the shown thickness, and accordingly uppersurface 55 may be at a different elevational height at regions of digitline 54 that are not visible in FIG. 6. Structure 102 can similarly beformed to be a line extending into and out of the page relative to theview of FIG. 6, and upper surface 105 can similarly have differentelevational heights relative to base 52 at regions of structure 102 thatare not visible in the view of FIG. 6. However, upper conductive surface105 is at the same elevational height over base 52 as is upperconductive surface 55 of the digit line in at least the regions of thestructures 102 and 54 visible in FIG. 6.

Structure 102 is shown comprising a stack of materials, and specificallyis shown comprising conductive material 104 over an electricallyinsulative material 106. It is to be understood that structure 102 cancomprise any of numerous configurations which can include a conductivematerial alone, or a conductive material in combination with insulativematerials. Further, although conductive material 104 is shown as theuppermost material of the stack of spacer 102, it is to be understoodthat an electrically insulative cap could be formed over conductivematerial 104. Ultimately, however, an opening is typically formed whichextends to the uppermost conductive surface 105 of structure 102, andaccordingly such opening would extend through any insulative cap formedover uppermost surface 105.

Structure 102 is beneath a portion of capacitor 58, and in the shownaspect of the invention is beneath horizontally-extending segment 68 ofcapacitor plate electrode 62.

Referring to FIG. 7, openings 120 and 122 are formed through layer 56 toupper conductive surfaces 55 and 105, respectively. Openings 120 and 122can be referred to as first and second openings in the discussion thatfollows. Opening 120 is identical to the opening 70 discussed previously(FIG. 4). Opening 122 is in an identical location as the opening 72discussed previously (FIG. 4), but unlike opening 72 extends entirelythrough capacitor dielectric 64 and capacitor plate electrode 62.Opening 122 thus has a periphery which includes an electricallyconductive portion of electrode 62. Such electrically conductive portionof the periphery of opening 122 is labeled as 124 in FIG. 7. Openings120 and 122 can be referred to as being formed through first and secondinsulative materials, respectively. In the shown aspect of the inventionthe first and second insulative materials are comprised by a commonlayer, but, as discussed above, the first and second insulativematerials can differ from one another in other aspects of the invention.

Since conductive surfaces 55 and 105 are at about the same elevationalheight as one another (and preferably are at an identical elevationalheight within the tolerances of a semiconductor fabrication process),openings 120 and 122 will be about the same depth as one another (andpreferably will be at an identical depth to one another within thelimitations of tolerances associated with a particular fabricationprocess).

In particular aspects of the invention, upper surface 105 can beconsidered a portion of a semiconductor substrate. Further, surface 105will ultimately be suitable for electroless plating. When surface 105 issuitable for electroless plating, the combination of structure 102 andsemiconductor base 52 can be considered a semiconductor substrate havingthe surface 105 suitable for electroless plating. Layer 62 can beconsidered an electrically conductive node, and accordingly opening 122can be considered to be formed through the electrically conductive nodeand to the surface 105 suitable for electroless plating.

Upper surfaces 55 and 105 can be formed to be suitable for initiatingelectroless plating by patterning materials 54 and 104 from compositionssuitable for electroless plating and/or by activating upper surfaces ofmaterials 54 and 104 after formation of openings 120 and 122.Accordingly, upper surfaces 55 and 105 can be suitable for electrolessplating prior to provision of layer 56; or can be rendered suitable byactivation occurring after formation layer 56, and specifically afterformation of openings 120 and 122 extending through layer 56. Inpreferred aspects, surface 105 of material 104 is identical incomposition to surface 55 of material 54. In such aspects, surfaces 55and 105 can comprise one or more of palladium, zinc, silver, nickel andcobalt. It can be preferred that surfaces 55 and 105 comprise one orboth of nickel and cobalt in particular semiconductor processingapplications.

Referring to FIG. 8, conductive material 80 is electroless plated withinopenings 120 and 122. Conductive material 80 can comprise, consistessentially of, or consist or one or more of palladium, zinc, silver,nickel and cobalt; and in particular aspects will consist essentiallyof, or consist of one or both of nickel and cobalt. The electrolessplating of material 80 can comprise conventional methods. For instance,the electroless plating can be conducted utilizing one or both of cobaltsulfate and nickel sulfate together with appropriate reducing agents,such as, for example, ammonium hypophosphite and/ordimetal-amino-borane. Conductive material 80 would typically comprisesome phosphorous and/or boron in addition to the electroless-platedmetal due to boron and/or phosphorous being present in reducing agentsutilized during the electroless-plating process. Accordingly, conductivematerial 80 can, in particular aspects, comprise, consist essentiallyof, or consist of one or more of palladium, zinc, silver, nickel andcobalt, in combination with one or both of phosphorous and boron.Choosing one or more of palladium, zinc, silver, nickel and cobalt canenable a plating bath to be made stable, and yet still sufficient toinitiate plating of material 80 on materials 54 and 104 but not onmaterials 62 and 64. The materials 62 and 64 would need appropriateactivation (with, for example, one or more of Pd, Sn, Zn, etc) forplating to initiate thereon.

The conductive material within openings 120 and 122 forms conductiveinterconnects 130 and 132, respectively. Conductive interconnect 130extends to structure 54. As discussed previously, structure 54 cancomprise a digit line, and accordingly conductive interconnect 130 canbe utilized for interconnecting the digit line to other circuitry (notshown). Conductive interconnect 132 extends to capacitor plateelectrode, and can thus be utilized for connecting plate electrode 62 toother circuitry (not shown). Conductive interconnect 132 also extends toconductive material 104. However, in typical processing conductivematerial 104 will be electrically isolated from any circuitry other thanconductive interconnect 132, and accordingly will be an electricaldead-end (or terminus).

Referring to FIG. 9, upper surfaces of electrical interconnects 130 and132 are planarized. Such can be accomplished utilizing, for example,chemical-mechanical polishing. Interconnects 130 and 132 are thenconnected to appropriate circuitry 134 and 136, respectively.Accordingly, interconnect 130 forms an electrical contact betweencircuitry 134 and structure 54 (with structure 54 being, for example, adigit line), and interconnect 132 forms an electrical contact betweencircuitry 136 and capacitor plate electrode 62.

Various modifications can be made to the shown aspect of the invention,as will be understood by persons of ordinary skill in the art. Forinstance, although conductive interconnect 132 is shown extendingthrough both dielectric material 64 and capacitor electrode 62, theinvention can encompass other aspects (not shown) in which capacitorelectrode 62 extends beyond dielectric material 64, and in which theinterconnect extends only through capacitor electrode 62 rather thanthrough both capacitor 62 and dielectric material 64. As another exampleof a modification that can be incorporated into aspects of theinvention, interconnect 132 can be formed to be adjacent an end ofelectrode 62 so that the conductive interconnect 132 is formed besideelectrode 162, rather than through the electrode. As another example,processing of the present invention can be utilized to form electricalconnection to a node 62 other than a capacitor electrode.

The structure of FIG. 9 can be, in particular aspects, considered tocomprise a digit line 54 and a spacer structure 102 which have shownregions with upper surfaces 55 and 105, respectively, at about the sameelevational height as one another. The structure further comprises alayer 56 supported by a base (or substrate) 52, and a capacitorstructure supported by the layer. A first conductive interconnect 130extends from the digit line and through the layer 56; and a secondconductive interconnect 132 extends from spacer structure 102, throughcapacitor electrode 62 and dielectric material 64 (and not throughcapacitor electrode 60). The first and second electrical interconnects130 and 132 were formed simultaneously during the same electrolessplating procedure, and accordingly comprise the same composition as oneanother.

The conductive interconnects 130 and 132 can be formed in relativelyhigh-aspect ratio openings, with such openings being formed to anysuitable depth, including, for example, depths of greater than or equalto about 3 microns. Thus, layer 56 can have a thickness of at leastabout 3 microns in the vicinity proximate the shown region of digit line54, and can also comprise a thickness of at least about 3 micronsproximate the shown region of spacer structure 102.

Although capacitor 58 and digit line 54 are shown adjacent one anotherin the aspect of the invention described with reference to FIG. 9, it isto be understood that numerous intervening devices (not shown) can beprovided in a space between the capacitor and the digit line, andaccordingly the capacitor and the digit line can be separated by arelatively large distance in other aspects of the invention (not shown).

As described with reference to FIGS. 7 and 8, upper surfaces 55 and 105of structures 54 and 104 can be suitable for electroless plating byeither forming such structures from compositions suitable for initiationof electroless plating, or by activation of compositions after exposingthe compositions through openings 120 and 122. A problem which can occurif surfaces 55 and 105 are activated after formation of openings 120 and122 is that such activation may also activate exposed portions 124 (FIG.7) of electrode 62. Accordingly, electroless plating may initiate notonly at surfaces 55 and 105, but also at exposed portions 124 ofelectrode 162. Such can lead to undesired closure of the middle portionof opening 122 before electroless-plated material 80 completely fills alower portion of the opening. This problem is illustrated in FIG. 10where a keyhole 150 is shown formed within conductive interconnect 132,as would occur if the portion of opening 122 (FIG. 7) were closed atabout the region of electrode 62 due to electroless plating initiationfrom exposed portions 124 (FIG. 7) of electrode 62. Accordingly, it canbe preferred to form upper surfaces 55 and 105 of an appropriatecomposition from which electroless plating will initiate withoutactivation, and further to form electrode 62 of a composition from whichelectroless plating will not initiate without activation. Theelectroless plating can then selectively initiate from surfaces 55 and105 without initiation from exposed portions 124 (FIG. 7) of electrode62, and accordingly keyhole 150 (FIG. 10) can be avoided.

FIGS. 11 and 12 illustrate a further aspect of the invention. Suchaspect can follow the processing stage of FIG. 4. Referring initially toFIG. 4, surface 55 of digit line 54 can comprise a suitable material forelectroless plating, while surface 63 comprises a material which is notsuitable for electroless plating. FIG. 11 shows construction 50 afterthe electroless plating has been conducted for sufficient time to formconductive material 80 within opening 70 to approximately the sameelevational level as the upper surface 63 of capacitor 62. Subsequently,upper surface 63 can be activated so the surface is now suitable forelectroless plating. Such activation is represented by the thin layer160 shown at upper surface 63 in FIG. 11. The activation can beconducted in accordance with procedures discussed previously in thisapplication.

After the activation of surface 63, the electroless plating can becontinued so that conductive material 80 fills opening 70, and alsofills opening 72. Since the openings 70 and 72 were approximately thesame depth as one another at the initiation of the second stage of theelectroless plating (i.e., at the process stage of FIG. 11), theconductive material 80 formed within openings 70 and 72 fills theopenings to about the same level. Such forms caps 160 and 162 overopenings 70 and 72, respectively, that are about the same size as oneanother. The caps can be removed by subsequent planarization, similarlyto the planarization of interconnects 130 and 132 discussed previouslywith reference to FIGS. 8 and 9.

The processing of FIGS. 4, 11 and 12 can be considered to comprise thefollowing sequence.

Initially, a semiconductor substrate 52 is provided, with such substratesupporting an electrically insulative material 56 and a pair ofelectrical nodes 54 and 62. Nodes 54 and 62 can be referred to as afirst node and a second node, respectively. A first opening 70 extendsthrough the electrically insulative material to the first node and asecond opening 72 extends through the electrically insulative materialto the second node at the processing stage of FIG. 4. The first node 54is at a first elevational height over the substrate and the second node63 is at a second elevational height over the substrate, with the firstelevational height being less than the second elevational height.Accordingly the first opening 70 is deeper than the second opening 72.The first electrical node has a first surface exposed within the firstopening and the second electrical node has a second surface exposedwithin the second opening. The first surface is suitable for electrolessplating and the second surface is not suitable for electroless platingat the processing stage of FIG. 4. Subsequently, a first conductivematerial 80 is electroless plated within the first opening to form afirst conductive material plug extending to a height within the firstopening that is about the same as the elevational height of the secondnode. Such forms the construction of FIG. 11.

The second surface is then activated to render the second surfacesuitable for electroless plating. Subsequently, a second conductivematerial is electroless plated within the first and second openings toform the construction of FIG. 12. The second conductive material withinthe first opening forms a second conductive material plug extendingupwardly from the first conductive material plug, and the secondmaterial within the second opening forms a second conductive materialplug extending upwardly from the second node. In the shown aspect of theinvention, the first and second electroless plated materials are thesame as one another, and specifically both correspond to material 80.However, it is to be understood that the invention also encompassesaspect in which the first and second electroless-plated materials arenot compositionally the same as one another.

FIG. 13 illustrates generally, by way of example but not by way oflimitation, an embodiment of a computer system 400 according to anaspect of the present invention. Computer system 400 includes a monitor401 or other communication output device, a keyboard 402 or othercommunication input device, and a motherboard 404. Motherboard 404 cancarry a microprocessor 406 or other data processing unit, and at leastone memory device 408. Memory device 408 can comprise various aspects ofthe invention described above. Memory device 408 can comprise an arrayof memory cells, and such array can be coupled with addressing circuitryfor accessing individual memory cells in the array. Further, the memorycell array can be coupled to a read circuit for reading data from thememory cells. The addressing and read circuitry can be utilized forconveying information between memory device 408 and processor 406. Suchis illustrated in the block diagram of the motherboard 404 shown in FIG.14. In such block diagram, the addressing circuitry is illustrated as410 and the read circuitry is illustrated as 412. Various components ofcomputer system 400, including processor 406, can comprise one or moreof the memory constructions described previously in this disclosure.

Processor device 406 can correspond to a processor module, andassociated memory utilized with the module can comprise teachings of thepresent invention.

Memory device 408 can correspond to a memory module. For example, singlein-line memory modules (SIMMs) and dual in-line memory modules (DIMMs)may be used in the implementation which utilize the teachings of thepresent invention. The memory device can be incorporated into any of avariety of designs which provide different methods of reading from andwriting to memory cells of the device. One such method is the page modeoperation. Page mode operations in a DRAM are defined by the method ofaccessing a row of a memory cell arrays and randomly accessing differentcolumns of the array. Data stored at the row and column intersection canbe read and output while that column is accessed.

An alternate type of device is the extended data output (EDO) memorywhich allows data stored at a memory array address to be available asoutput after the addressed column has been closed. This memory canincrease some communication speeds by allowing shorter access signalswithout reducing the time in which memory output data is available on amemory bus. Other alternative types of devices include SDRAM, DDR SDRAM,SLDRAM, VRAM and Direct RDRAM, as well as others such as SRAM or Flashmemories.

Memory device 408 can comprise memory formed in accordance with one ormore aspects of the present invention.

FIG. 15 illustrates a simplified block diagram of a high-levelorganization of various embodiments of an exemplary electronic system700 of the present invention. System 700 can correspond to, for example,a computer system, a process control system, or any other system thatemploys a processor and associated memory. Electronic system 700 hasfunctional elements, including a processor or arithmetic/logic unit(ALU) 702, a control unit 704, a memory device unit 706 and aninput/output (I/O) device 708. Generally, electronic system 700 willhave a native set of instructions that specify operations to beperformed on data by the processor 702 and other interactions betweenthe processor 702, the memory device unit 706 and the I/O devices 708.The control unit 704 coordinates all operations of the processor 702,the memory device 706 and the I/O devices 708 by continuously cyclingthrough a set of operations that cause instructions to be fetched fromthe memory device 706 and executed. In various embodiments, the memorydevice 706 includes, but is not limited to, random access memory (RAM)devices, read-only memory (ROM) devices, and peripheral devices such asa floppy disk drive and a compact disk CD-ROM drive. One of ordinaryskill in the art will understand, upon reading and comprehending thisdisclosure, that any of the illustrated electrical components arecapable of being fabricated to include memory constructions inaccordance with various aspects of the present invention.

FIG. 16 is a simplified block diagram of a high-level organization ofvarious embodiments of an exemplary electronic system 800. The system800 includes a memory device 802 that has an array of memory cells 804,address decoder 806, row access circuitry 808, column access circuitry810, read/write control circuitry 812 for controlling operations, andinput/output circuitry 814. The memory device 802 further includes powercircuitry 816, and sensors 820, such as current sensors for determiningwhether a memory cell is in a low-threshold conducting state or in ahigh-threshold non-conducting state. The illustrated power circuitry 816includes power supply circuitry 880, circuitry 882 for providing areference voltage, circuitry 884 for providing the first wordline withpulses, circuitry 886 for providing the second wordline with pulses, andcircuitry 888 for providing the bitline with pulses. The system 800 alsoincludes a processor 822, or memory controller for memory accessing.

The memory device 802 receives control signals 824 from the processor822 over wiring or metallization lines. The memory device 802 is used tostore data which is accessed via I/O lines. It will be appreciated bythose skilled in the art that additional circuitry and control signalscan be provided, and that the memory device 802 has been simplified tohelp focus on the invention. At least one of the processor 822 or memorydevice 802 can include a memory construction of the type describedpreviously in this disclosure.

The various illustrated systems of this disclosure are intended toprovide a general understanding of various applications for thecircuitry and structures of the present invention, and are not intendedto serve as a complete description of all the elements and features ofan electronic system using memory cells in accordance with aspects ofthe present invention. One of the ordinary skill in the art willunderstand that the various electronic systems can be fabricated insingle-package processing units, or even on a single semiconductor chip,in order to reduce the communication time between the processor and thememory device(s).

Applications for memory cells can include electronic systems for use inmemory modules, device drivers, power modules, communication modems,processor modules, and application-specific modules, and may includemultilayer, multichip modules. Such circuitry can further be asubcomponent of a variety of electronic systems, such as a clock, atelevision, a cell phone, a personal computer, an automobile, anindustrial control system, an aircraft, and others.

It is noted that relative elevational relationships are utilized todescribe the locations of various features to one another (e.g., upward,downward, etc are utilized) within this disclosure. It is to beunderstood that such terms are used to express relative relationsbetween the components only, and not to indicate a relationship of thecomponents relative to an external frame of reference. Thus, forexample, a feature described herein as projecting upwardly relative toanother feature may in fact appear to extend downwardly to a viewer inan external frame of reference relative to the feature.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A semiconductor processing method for forming an electrical contact,comprising: providing a semiconductor substrate which supports anelectrically insulative material and a pair of electrical nodes, theelectrical nodes being a first node and a second node, a first openingextending through the electrically insulative material to the first nodeand a second opening extending through the electrically insulativematerial to the second node, the first node being at a first elevationalheight over the substrate and the second node being at a secondelevational height over the substrate, the first elevational heightbeing less than the second elevational height and accordingly the-firstopening being deeper than the second opening, the first electrical nodehaving a first surface exposed within the first opening and the secondelectrical node having a second surface exposed within the secondopening, the first surface being suitable for electroless plating andthe second surface not being suitable for electroless plating;electroless plating a first conductive material within the first openingand from the first surface to form a first conductive material plugextending to a height within the first opening that is about the same asthe second elevational height; activating the second surface to renderthe second surface suitable for electroless plating; and afteractivating the second surface, electroless plating a second conductivematerial within the first and second openings, the second conductivematerial within the first opening forming a second conductive materialplug extending upwardly from the first conductive material plug, and thesecond material within the second opening forming a second. conductivematerial plug extending upwardly from the second surface.
 2. The methodof claim 1 wherein the first and second conductive materials arecompositionally the same as one another.
 3. The method of claim 1wherein the second conductive material plugs within the first and secondopenings extend to an upper surface of the electrically insulativematerial.
 4. The method of claim 1 wherein the second conductivematerial plugs within the first and second openings extend upwardlybeyond an upper surface of the electrically insulative material.
 5. Themethod of claim 1 wherein the first node is part of a digit line and thesecond node is part of a capacitor electrode.
 6. A semiconductorprocessing method for forming electrical contacts to a capacitorelectrode and a digit line, comprising: providing a semiconductorsubstrate, the semiconductor substrate supporting a digit line and aspacer structure, the digit line comprising a region and the spacerstructure comprising another region; the digit line region having anupper surface and the spacer structure region having another uppersurface, the digit line region upper surface being about the sameelevational height over the substrate as the spacer structure regionupper surface, the semiconductor substrate comprising a first insulativematerial over the digit line region and a second insulative materialover the spacer structure region, the semiconductor substrate comprisinga capacitor electrode supported by the substrate; forming openingsthrough the first and second insulative materials, the opening throughthe first insulative material being a first opening and extending to theupper surface of the digit line region, the opening through the secondinsulative material being a second opening and extending to the uppersurface of the spacer structure region, the second opening having aperiphery which includes an electrically conductive portion of thecapacitor electrode; and electroless plating a conductive materialwithin the first and second openings, the electroless plating initiatingfrom the upper surfaces of the digit line region and spacer structureregion, the electroless-plated material forming an electrical contact tothe digit line in the first opening and forming an electrical contact tothe capacitor electrode in the second opening.
 7. The method of claim 6wherein the capacitor electrode comprises one or more of TiN, WN, WSiand conductively-doped silicon, with the listed compositions being shownin terms of the elements contained therein rather than in terms of aparticular stoichiometry of the elements within the compositions.
 8. Themethod of claim 6 wherein the spacer structure is a dummy structure. 9.The method of claim 6 wherein the first and second insulative materialsare comprised by a common layer.
 10. The method of claim 9 wherein thecommon layer comprises BPSG.
 11. The method of claim 9 wherein thecommon layer comprises a thickness of at least about 3 microns over thedigit line region and spacer structure region.
 12. The method of claim 9wherein second opening extends through the capacitor electrode.
 13. Themethod of claim 11 wherein the second opening extends through a segmentof the capacitor electrode, and wherein the common layer comprises athickness of less than or equal to about 1 micron over the segment ofthe capacitor electrode.
 14. The method of claim 6 wherein the capacitorelectrode is a capacitor plate electrode, the method further comprising:forming a capacitor storage node electrode supported by the substrate;forming at least one dielectric material over the capacitor storage nodeelectrode; and forming the capacitor plate electrode over the at leastone dielectric material.
 15. The method of claim 14 wherein the secondopening extends through the capacitor plate electrode and the at leastone dielectric material, but does not extend through the capacitorstorage node electrode.
 16. The method of claim 6 wherein the uppersurfaces of the digit line region and spacer structure region have thesame composition as one another prior to formation of the layer.
 17. Themethod of claim 16 wherein the upper surfaces of the digit line regionand spacer structure region have a suitable composition for theelectroless plating prior to the formation of the layer.
 18. The methodof claim 17 wherein the suitable composition for the electroless platingcomprises one or more of palladium, silver, zinc, nickel and cobalt. 19.The method of claim 17 wherein the suitable composition for theelectroless plating comprises one or both of nickel and cobalt.
 20. Themethod of claim 16 wherein the upper surfaces of the digit line regionand spacer structure region do not have a suitable composition for theelectroless plating prior to the formation of the layer, and areactivated after the formation of the first and second openings to besuitable for the electroless plating.
 21. The method of claim 20 whereinthe activation comprises provision of a sufficient amount of one or moreof palladium, silver, zinc, nickel and cobalt on the upper surfaces ofthe digit line region and spacer structure region to make theelectroless plating spontaneous.